Sample pretreatment process for food detection

Abstract

The invention discloses a sample pretreatment process for food detection, which comprises the following steps: S1, sample pretreatment: homogenizing a sample, uniformly mixing the homogenized sample with a DES solvent with a preset concentration and a preset type to obtain a mixture A, and conveying the mixture A to extraction equipment; s2, synergistic extraction, microwave and ultrasonic treatment equipment performs microwave and ultrasonic synergistic extraction on the mixture A at preset microwave power, preset ultrasonic intensity, preset temperature, preset time and preset pressure to ensure that a solvent permeates to obtain a mixture B; s3, on-line separation: carrying out solid-liquid separation on the mixture B through a ceramic membrane filter, and carrying out back flushing on filter residues by using DES with preset concentration and preset amount so as to improve the recovery rate, so that a pretreated sample C is obtained. According to the sample pretreatment process for food detection, the sample is extracted through cooperation of the energy field synergistic effect of microwaves and ultrasonic waves and the DES solvent, and the extraction efficiency can be effectively improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of food detection, in particular to a sample pretreatment process for food detection. BACKGROUND

[0002] The sample pretreatment process in food detection is a key step to ensure the accuracy and sensitivity of detection, which involves the cross-application of multiple fields such as chemistry, biology, material science and automation. Traditional sample pretreatment techniques include physical treatment (such as homogenization, filtration, centrifugation, etc.), chemical extraction (such as solvent extraction such as Soxhlet extraction and liquid-liquid extraction, distillation, etc.), purification and concentration (such as solid phase extraction, gel permeation chromatography, etc.). Based on the above various types of pretreatment methods, the purpose of the sample pretreatment process in food detection is to complete the crushing, impurity removal and extraction and separation of the sample to obtain a processed product that meets the subsequent detection requirements.

[0003] At present, the sample pretreatment for food detection includes three main development directions of green extraction technology, high-efficiency separation technology and automated extraction. The existing high-efficiency separation technology includes but is not limited to magnetic solid phase extraction technology and molecular imprinting technology, and the automated extraction is completed through automatic solid phase extraction instruments, microwave digestion systems and other automatic equipment. However, the above sample pretreatment methods still have problems such as large amount of organic solvent used, insufficient standardization, etc., resulting in high processing cost, high pollution, narrow detection project adaptation range, etc. SUMMARY

[0004] Therefore, it is necessary to provide a sample pretreatment process for food detection in view of the technical problem of insufficient standardization of the existing sample pretreatment process for food detection.

[0005] A sample pretreatment process for food detection, which comprises the following steps: S1, sample pretreatment, homogenizing the sample, and uniformly mixing the homogenized sample with a DES solvent of a preset concentration and a preset type to obtain a mixture A, and conveying the mixture A to an extraction device; S2, synergistic extraction, the microwave and ultrasonic treatment device performs microwave and ultrasonic synergistic extraction on the mixture A at a preset microwave power, a preset ultrasonic intensity, a preset temperature, a preset time and a preset pressure to ensure solvent penetration to obtain a mixture B; S3, online separation, the mixture B is subjected to solid-liquid separation through a ceramic membrane filter, and the filter residue is subjected to reverse flushing with a DES of a preset concentration and a preset amount to improve the recovery rate, and then a pretreated sample C is obtained.

[0006] In one of the embodiments, the pre-set type of the DES solvent in the step S1 includes one of choline chloride-glycerol eutectic solvent, betaine-lactic acid eutectic solvent and citric acid-glucose eutectic solvent.

[0007] In one of the embodiments, the choline chloride-glycerol eutectic solvent is prepared by choline chloride and glycerol with a molar ratio of 1:2.

[0008] In one of the embodiments, the betaine-lactic acid eutectic solvent is prepared by betaine and lactic acid with a mass ratio of 1:3.

[0009] In one of the embodiments, the citric acid-glucose eutectic solvent is prepared by citric acid and glucose with a mass ratio of 1:1.

[0010] In one of the embodiments, the step S1 includes the following steps: S11, selecting the DES solvent according to the food detection item: when the detection item is pesticide residue detection, the DES solvent is choline chloride-glycerol eutectic DES solvent, and the dosage of the DES solvent is 3-5 mL / g sample; when the detection item is polyphenol detection, the DES solvent is betaine-lactic acid eutectic DES solvent, and the dosage of the DES solvent is 5-8 mL / g sample; when the detection item is heavy metal detection, the DES solvent is citric acid-glucose eutectic solvent, and the dosage of the DES solvent is 4-6 mL / g sample; S12, homogenizing the sample, and uniformly mixing the homogenized sample with the DES solvent selected in the step S11 to obtain a mixture A, and conveying the mixture A to an ultrasonic premixing device.

[0011] In one of the embodiments, the step S1 further includes the following steps: S13, the mixture A is subjected to ultrasonic premixing by the ultrasonic premixing device under the process conditions of a parameter of 40 kHz, a power of 100 W and a time of 1 min, so as to ensure solvent penetration.

[0012] In one of the embodiments, in the step S12, the particle size of the homogenized sample is controlled to be below 100 μm.

[0013] In one of the embodiments, in the step S2, the microwave power is set to 200-600 W, the ultrasonic intensity is set to 50-300 W / cm 2 , the temperature is set to 30-80℃, the pressure is set to 0.1-1.5 MPa, and the treatment time is set to 2-10 min, so as to improve the extraction rate.

[0014] In one of the embodiments, in the step S2, the microwave power is set to 350 W, the ultrasonic intensity is set to 150 W / cm 2The temperature is set to 45±2℃, the pressure is set to 0.8 MPa, and the processing time is set to 4 min, so as to improve the extraction rate.

[0015] In one of the embodiments, in the step S3, the ceramic membrane filter pore size is set to 0.45 μm, and the transmembrane pressure difference is set to 0.3 bar.

[0016] In one of the embodiments, in the step S3, the amount of DES is set to 2 mL, so as to improve the recovery rate.

[0017] In one of the embodiments, in the step S2, in order to deal with the emergency situation that may occur during the processing, the step S2 further includes the following emergency measures: when the solvent of the mixture A boils or the temperature is greater than 80℃, the cooling DES solvent is injected into the mixture A at a flow rate of 1 mL / s, the microwave power is reduced to 200 W, and the processing time is extended by 1 min; when the ultrasonic probe cavitation occurs during the extraction of the mixture A, the pressure is compensated, specifically, the pressure is increased by 0.2 MPa, and the ultrasonic frequency is switched to 25 kHz; when the matrix high oil interferes, 5% NaCl solution of the preset two is added to the mixture A for demulsification, and the processing temperature is increased to 60℃ for 30 s.

[0018] The food sample pretreatment process described above is processed by the synergistic extraction in the step S2, the mixture A is subjected to microwave and ultrasonic synergistic extraction by the microwave and ultrasonic processing equipment at a preset microwave power, a preset ultrasonic intensity, a preset temperature, a preset time and a preset pressure, so as to ensure that the solvent penetrates to obtain the mixture B. Compared with the traditional sample extraction method, the sample is extracted by the energy field synergistic effect of the microwave and ultrasonic and the DES solvent, which can effectively improve the extraction efficiency under the premise of reducing the amount of organic solvent, greatly compress the extraction time, and by changing the DES solvent, different detection requirements can be met, which greatly improves the adaptability and flexibility of the sample pretreatment supply of the present application, and is suitable for being integrated into the automatic detection line as a standardized pretreatment module. DETAILED DESCRIPTION

[0019] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a lot of specific details are set forth in order to fully understand the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0020] In the description of the present application, it is to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like is based on the orientation or positional relationship shown in the following and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0021] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is at least two, such as two, three, etc., unless otherwise explicitly specified and limited.

[0022] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, it can be the internal communication of two elements or the interaction relationship of two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0023] In the present application, unless otherwise explicitly specified and limited, the first feature is "on" or "under" the second feature, which can be direct contact between the first and second features, or indirect contact between the first and second features through intermediate medium. Moreover, the first feature "above", "above" and "above" the second feature can be directly above or obliquely above the first feature, or only indicate that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature can be directly below or obliquely below the first feature, or only indicate that the horizontal height of the first feature is less than that of the second feature.

[0024] It is to be understood that when an element such as a layer, region or substrate is referred to as being "on" or "connected to" another element, it can be directly on or connected to the other element or intervening elements can be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element, there are no intervening elements present. It will be understood that, when a member is referred to as being "coupled" or "connected" to another member, it can be directly coupled or connected to the other member or intervening members can be present. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," when preceding the syntax elements A, B, and / or C, mean that the solution include A alone; or B alone; or C alone; or any combination of these elements A, B, and C.

[0025] The present application discloses a sample pretreatment process for food detection, which comprises the following steps: S1, sample pretreatment, homogenizing the sample, uniformly mixing the homogenized sample with a DES solvent of a preset concentration and a preset type to obtain a mixture A, and conveying the mixture A to an extraction device; S2, synergistic extraction, the microwave and ultrasonic treatment device performs microwave and ultrasonic synergistic extraction on the mixture A at a preset microwave power, a preset ultrasonic intensity, a preset temperature, a preset time and a preset pressure to ensure solvent penetration to obtain a mixture B; S3, online separation, the mixture B is subjected to solid-liquid separation through a ceramic membrane filter, and the filter residue is subjected to reverse flushing with a DES of a preset concentration and a preset amount to improve the recovery rate, and then a sample C after pretreatment is obtained.

[0026] Further, in the above step S1, the preset type of the DES solvent includes one of a choline chloride-glycerol eutectic solvent, a betaine-lactic acid eutectic solvent and a citric acid-glucose eutectic solvent. In one embodiment, the choline chloride-glycerol eutectic solvent is prepared from choline chloride and glycerol in a molar ratio of 1:2; in one embodiment, the betaine-lactic acid eutectic solvent is prepared from betaine and lactic acid in a mass ratio of 1:3; and in one embodiment, the citric acid-glucose eutectic solvent is prepared from citric acid and glucose in a mass ratio of 1:1.

[0027] Further, the above step S1 comprises the following steps: S11, selecting the DES solvent according to the food detection item: when the detection item is pesticide residue detection, the DES solvent is a choline chloride-glycerol eutectic DES solvent, and the amount of the DES solvent is 3-5 mL / g of the sample; when the detection item is polyphenol detection, the DES solvent is a betaine-lactic acid eutectic DES solvent, and the amount of the DES solvent is 5-8 mL / g of the sample; and when the detection item is heavy metal detection, the DES solvent is a citric acid-glucose eutectic solvent, and the amount of the DES solvent is 4-6 mL / g of the sample; S12, homogenize the sample, and mix the homogenized sample with the DES solvent selected in step S11 to obtain a mixture A, and deliver the mixture A to an ultrasonic premixing device.

[0028] Further, the step S1 described above further comprises the following steps: S13, the mixture A is subjected to ultrasonic premixing by the ultrasonic premixing device under the process conditions of 40 kHz, 100 W, and 1 min to ensure solvent penetration.

[0029] In one embodiment, further, in the step S12 described above, the particle size of the homogenized sample is controlled to be below 100 pm.

[0030] Further, in the step S2 described above, the microwave power is set to 200-600 W, the ultrasonic intensity is set to 50-300 W / cm 2 , the temperature is set to 30-80℃, the pressure is set to 0.1-1.5 MPa, and the processing time is set to 2-10 min to improve the extraction rate. In one embodiment, in the step S2 described above, the microwave power is set to 350 W, the ultrasonic intensity is set to 150 W / cm 2 , the temperature is set to 45±2℃, the pressure is set to 0.8 MPa, and the processing time is set to 4 min to improve the extraction rate.

[0031] Further, in the step S3 described above, the pore size of the ceramic membrane filter is set to 0.45 pm, and the transmembrane pressure difference is set to 0.3 bar.

[0032] Further, in the step S3 described above, the amount of DES is set to 2 mL to improve the recovery rate.

[0033] Further, in the step S2 described above, in order to deal with possible emergency situations during the processing, the step S2 further comprises the following emergency measures: when the solvent of the mixture A boils or the temperature is greater than 80℃, inject a cooling DES solvent into the mixture A at a flow rate of 1 mL / s, and reduce the microwave power to 200 W, while extending the processing time by 1 min; when cavitation occurs in the ultrasonic probe during the extraction of the mixture A, perform pressure compensation, specifically, increase by 0.2 MPa, and switch the ultrasonic frequency to 25 kHz; when the substrate is high in oil and fat and interferes, add a pre-set 5% NaCl solution to the mixture A to break the emulsion, and increase the processing temperature to 60℃ for 30 s.

[0034] To sum up, the sample pretreatment process for food detection disclosed by the present application ensures that the solvent penetrates to obtain mixture B through the synergistic extraction treatment in step S2, microwave and ultrasonic treatment equipment, microwave, ultrasonic synergistic extraction of mixture A at a preset microwave power, a preset ultrasonic intensity, a preset temperature, a preset time and a preset pressure, compared with the traditional sample extraction method, the present application can effectively improve the extraction efficiency under the premise of reducing the amount of organic solvent, greatly compress the extraction time, at the same time, by changing the DES solvent, it can adapt to different detection requirements, greatly improve the adaptability and flexibility of the sample pretreatment supply of the present application, and it is suitable for being integrated into the automatic detection line as a standardized pretreatment module.

[0035] The technical features of the above-described embodiments can be combined in any manner. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, but as long as the combinations of the technical features do not contradict, they should be considered within the scope of the present disclosure.

[0036] The above-described embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, some modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A sample pretreatment process for food testing, characterized in that: The steps include: S1. Sample pretreatment: homogenize the sample and evenly mix the homogenized sample with a DES solvent of a preset concentration and type to obtain a mixture A, which is then transported to the extraction equipment; S2. Co-extraction: The microwave and ultrasonic processing equipment performs microwave and ultrasonic co-extraction on the mixture A at a preset microwave power, preset ultrasonic intensity, preset temperature, preset time and preset pressure to ensure solvent penetration to obtain the mixture B; S3, online separation, the mixture B is passed through a ceramic membrane filter for solid-liquid separation, and the filter residue is backwashed with a preset concentration and a preset amount of DES to improve the recovery rate, thereby obtaining a sample C that has completed pretreatment.

2. The food sample pretreatment process according to claim 1, characterized in that: In the above step S1, the preset type of the DES solvent includes one of a choline chloride-glycerol eutectic solvent, a betaine-lactic acid eutectic solvent, and a citric acid-glucose eutectic solvent.

3. The food sample pretreatment process according to claim 2, characterized in that: The above step S1 includes the following steps: S11. Select the DES solvent according to the food testing item: when the testing item is pesticide residue testing, the DES solvent is choline chloride-glycerol eutectic DES solvent, and the DES solvent dosage is 3-5 mL / g sample; when the testing item is polyphenol testing, the DES solvent is betaine-lactic acid eutectic DES solvent, and the DES solvent dosage is 5-8 mL / g sample; when the testing item is heavy metal testing, the DES solvent is citric acid-glucose eutectic DES solvent, and the DES solvent dosage is 4-6 mL / g sample; S12. Homogenize the sample, and evenly mix the homogenized sample with the DES solvent selected in step S11 to obtain a mixture A, and transport the mixture to an ultrasonic premixing device.

4. The food sample pretreatment process according to claim 3, characterized in that: The above step S1 further includes the steps of: S13. Mixture A is ultrasonically premixed using an ultrasonic premixing device under the process conditions of 40 kHz, 100 W, and 1 min.

5. The food sample pretreatment process according to claim 3, characterized in that: In the above step S12, the particle size of the sample is controlled to be less than 100 μm after homogenization.

6. The food sample pretreatment process according to claim 1, characterized in that: In the above step S2, the microwave power is set to 200-600W, and the ultrasonic intensity is set to 50-300W / cm 2 , the temperature is set to 30-80℃, the pressure is set to 0.1-1.5MPa, and the processing time is set to 2-10min.

7. The food sample pretreatment process according to claim 1, characterized in that: In the above step S2, the microwave power is set to 350W and the ultrasonic intensity is set to 150W / cm 2 , the temperature was set to 45±2℃, the pressure was set to 0.8MPa, and the processing time was set to 4min.

8. The food sample pretreatment process according to claim 1, characterized in that: In the above step S3, the pore size of the ceramic membrane filter is set to 0.45 μm, and the transmembrane pressure difference is set to 0.3 bar.

9. The food sample pretreatment process according to claim 1, characterized in that: In the above step S3, the amount of DES is set to 2 mL.

10. The food sample pretreatment process according to claim 1, characterized in that: In the above-mentioned step S2, step S2 also includes the following emergency measures: when the solvent of mixture A boils or the temperature is greater than 80°C, cooled DES solvent is injected into mixture A at a flow rate of 1 mL / s, and the microwave power is reduced to 200 W, and the treatment time is extended by 1 min; when cavitation of the ultrasonic probe occurs during the extraction of mixture A, pressure compensation is performed, specifically by increasing the pressure by 0.2 MPa, and the ultrasonic frequency is switched to 25 kHz; when high-fat matrix interference occurs in mixture A, a preset amount of 5% NaCl solution is added to mixture A for demulsification, and the treatment temperature is increased to 60°C for 30 seconds.